Characterization of Listeria monocytogenes recovered from imported cheese contributed to the National PulseNet Database by the U.S. Food and Drug Administration from 2001 to 2008.

Imported foods must meet the same U.S. Food and Drug Administration (FDA) standards as domestic foods. The FDA determines whether an imported food is in compliance with the Federal Food, Drug, and Cosmetic Act. Pursuant to its regulatory activities, the FDA conducts compliance surveillance on imported foods offered for entry into the U.S. commerce. The National PulseNet Database is the molecular surveillance network for foodborne infections and is widely used to provide real-time subtyping support to epidemiologic investigations of foodborne diseases. FDA laboratories use pulsed-field gel electrophoresis to subtype foodborne pathogens recovered from imported foods and submit the molecular patterns to the National PulseNet Database at the Centers for Disease Control and Prevention. There were 60 isolates of Listeria monocytogenes in the FDA Field Accomplishment and Compliance Tracking System from 2001 to 2008 due to cheese imported from the following countries: Mexico (n=21 isolates), Italy (19), Israel (9), Portugal (5), Colombia (3), Greece (2), and Spain (1). We observed genetic diversity of L. monocytogenes isolates and genetic relatedness among strains recovered from imported cheese products coming to the United States from different countries. Consistent characterization of L. monocytogenes isolates recovered from imported cheeses, accompanied by epidemiologic investigations to ascertain human illness associated with these strains, could be helpful in the control of listeriosis acquired from imported cheeses.